Economist brains

A shipwreck victim washes up on an unknown South Seas island, one with a surprisingly developed economic system, if based on cannibalism. Wandering penniless through the local meat market, he notices the stall selling human brains in many appetizing forms has an interesting pricing scheme; the sign over 3 glistening, bloody buckets of brains reads:

Accountant brains: 15 cowrie shells/kilo

Lawyer brains: 25 shells/kilo

Economist brains: 50 shells/kilo.

“Hey,” says the traveller, “I guess those economist brains must be pretty special. What is it, do they like, taste better?”

“No way dude,” says the brains butcher. “You know how many economists you have to kill to get a kilo of brains?!”